A question for the electronics chaps , I would like to build a circuit that would charge up a bank of capacitors to anywhere between say 10v to 35v and when charged to the set voltage disconnect the power supply from the capacitor bank .

Any pointers ?

Rob

Nope, no Pointers, mates got a Staffy

Depends on what you want to do, I'd use a PIC, one analogue channel to read a pot, and set the reqd. voltage and another to read the cap. bank volts.

Use one digital channel to drive a relay to disconnect when it's up to what you want.

How big is this cap. bank anyway ?? Not a good idea to try to charge a damn great heap of the things from zero without some attempt at a current limiter. A big cap. is close to a short circuit at initial switch on ... Stresses the rectifier no end ...

You going to Doncaster BTW ???

Dave

Logged

I have a few modest talents. Knowing what I'm doing isn't one of them.

Not having any real idea of how these things work, it seems to me to use a thyristor as the switching element as these turn off anyway when the current drops below the holding value and it wont switch on again until another gate pulse arrives ...

D.

Logged

I have a few modest talents. Knowing what I'm doing isn't one of them.

A question for the electronics chaps , I would like to build a circuit that would charge up a bank of capacitors to anywhere between say 10v to 35v and when charged to the set voltage disconnect the power supply from the capacitor bank .

Any pointers ?

Rob

The details depend on things like how: how big the caps are, how fast you want to charge them, and what your input voltage to this circuit will be.

But essentially you would use a current limited power supply set to the target voltage and a diode. Very simple for small (ie <=10A) currents.PK

I've checked all the elec caps, the're round the right way, all the chips are right way round in the correct places, I unsoldered one leg of each diode ( 4 in total ) and tested those, the're the right way.the transistors are the right way according to the silkscreen.

I even pulled all the chips to check if I folded a leg over inserting them, all OK.

with 1K load resistors I don't expect the transistors to run hot but the TO-92 cased 78L08 regulator added to the Chinese circuit could (depending the current taken by the receiver and the volt drop across the regulator)

The SMT components were very easy to solder despite having absolutely zero previous experience with these. I used 0.25mm Pb/Sn solder, a pair of curved pointy tweezers and the largest chisel tip for the soldering iron that would fit on the little pads. No problems at all. In fact they were the easiest and tidiest part of the build. Some of the through hole components were a bit fiddly (the sliding switches especially) and the end product wasn't as tidy as the SMT bits but it all worked first time, so I can't really complain.

The acrylic case looks nice but there were a couple of problems. Firstly, the tabs for the sliding switches snapped the first time I toggled them and I had to remove them all. Secondly, one of the sides had slightly oversized tabs which snapped the plastic around the holes where it fits into.

Overall, it was a nice little project. Well worth the money. Now I need to learn how to use an oscilloscope.